In the days of Charles Darwin

What determines the color of your eyes, hair or skin? What determines your height, complexion or resemblance to one or both parents? What dictates that on the upper face of your fingertips grows a protective nail and that the opposite face is a soft pad?

In Charles Darwin's day, the answers to these unknowns were shrouded in darkness. Darwin himself was fascinated by the way characters are transmitted from one generation to the next, although he knew little about the laws of genetics and even less about the intracellular mechanisms that regulate heredity. Modern biologists have been studying human genetics and the detailed instructions carried by the extraordinary DNA molecule for decades. obviously, the big question is where those instructions came from.